1. Technical Field
The present invention relates to a solid-state imaging device in which pixel sections including photoelectric conversion sections are arranged in a matrix.
2. Background Art
In recent years, a MOS (Metal Oxide Semiconductor) type solid-state imaging device is gaining attention as a device capable of being driven with low power consumption and shooting at high speed, and is starting to be installed in various fields such as a cell phone camera, an in-vehicle camera and a surveillance camera.
FIG. 6 shows a circuit configuration of a typical MOS type solid-state imaging device. As shown in FIG. 6, pixel sections 100 including photoelectric conversion sections (photodiodes) 101 configure an imaging region by being arranged in a matrix. Charges that are photoelectrically converted by photoelectric conversion sections 101 are transferred to floating diffusion layers (floating diffusion) 102 by transfer transistors 103. The charges that were transferred to floating diffusion layer 102 are amplified in amplifying transistors 104, and are transmitted to output signal line 111 through selected transistors 106 selected by vertical shift register 108. Further, the amplified charges are outputted from output terminal 112 through horizontal shift registers 109. Note that, excessive charges stored in floating diffusion layer 102 are discharged by reset transistors 105 whose drain regions are connected to power lines 107.
FIG. 7 shows a cross sectional configuration of pixel sections 100 according to a conventional example (for example, refer to Unexamined Japanese Patent Publication No. 2006-210919). As shown in FIG. 7, p-type epitaxial layer 203 is formed on p-type semiconductor substrate 201. Each pixel section 100 is partitioned by element isolations 207, and one of green filter 227G that transmits green light, red filter 227R that transmits red light, and blue filter 227B that transmits blue light is arranged.
At an upper portion of p-type epitaxial layer 203, p-type first impurity injection regions 219 and n-type second impurity injection regions 217 at underneath p-type first impurity injection regions 219 are arranged, thereby configuring photodiodes that are the photoelectric conversion sections. Junction portions of n-type second impurity injection regions 217 and p-type epitaxial layer 203 also become the photoelectric conversion sections. At portions of p-type epitaxial layer 203 under each of second impurity injection regions 217, p+-type first embedded barrier layers 205 are continuingly formed. That is, a concentration of p-type impurities doped in first embedded barrier layers 205 is higher than a concentration of p-type impurities doped in p-type epitaxial layer 203.
Second embedded barrier layers 211 are formed above first embedded barrier layers 205 in p-type epitaxial layer 203 for pixel sections 100 provided with green filter 227G and blue filter 227B. Further, third embedded barrier layer 215 is formed on second embedded barrier layer 211 for pixel section 100 provided with blue filter 227B. Here, in second embedded barrier layer 211 and third embedded barrier layer 215, the p-type impurities are doped therein and have concentrations of substantially the same as the impurity concentration of first embedded barrier layer 205. Further, an upper portion of each of embedded barrier layers 205, 211 and 215 is separated from second impurity injection regions 217.
As described above, a crosstalk is prevented by adjusting widths and positions of depletion regions of the photodiodes depending on wavelength of light incident on respective pixel sections 100.
Further, there is a conventional art that prevents the crosstalk which changes an injection depth of the n-type impurities configuring the photodiodes, depending on the wavelength of light incident on the respective pixel sections and adjusts the depletion regions of the photodiodes, for example by forming the photodiode of the pixel section having the blue filter to be shallow and the photodiode of the pixel section having the red filter to be deep.